Writing an object description from a requirement

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A requirement says: 'The library records each book's title and number of pages.' Which object description fits best?

A Book | title: string, pages: integer | getTitle(), getPages()

B Library | books: array | addBook()

2. Requirement: 'A student's name and age must be stored and the age can be changed.' Which description is correct?

A Student | name: integer, age: string | getAge(), setAge(newAge)

B Student | name: string, age: integer | getAge(), setAge(newAge)

3. Requirement: 'A pet shop tracks each dog's name and weight in kilograms.' Which attribute list is better?

A name: string, weight: float, favouriteColour: string, owner: string

B name: string, weight: float

4. Which method name follows camelCase for reading the attribute 'totalMarks'?

A getTotalMarks()

B get_total_marks()

5. Requirement: 'The system must show a car's registration and let the owner update its odometer reading.' Which methods suit the Car object?

A getRegistration(), setOdometer(newReading)

B setRegistration(newReg), deleteCar(), driveToSchool()

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Student \| name: string, age: integer \| getAge(), setAge(newAge)		AStudent \| name: string, age: integer \| getAge(), setAge(newAge)
2name: string, age: integer		BA complete object description: the object name, its attributes with data types, then its methods
3A requirement says a library must record each book's title and number of pages, so the object is Book and only those two attributes are needed		CThe attributes part of the description: each data item the object stores, with its data type
4Methods are named with the same convention as the rest of the program (camelCase), starting with a verb such as get or set		DThe attributes have no data types. They should be written as name: string, age: integer.
5Student \| name, age \| getAge(), setAge(newAge)		EfavouriteColour is not needed by the requirement. Only relevant attributes should be included, so it should be removed.
6Student \| name: string, age: integer, favouriteColour: string \| getAge()		FBook \| title: string, pages: integer \| getTitle(), getPages()

Definitions

object description

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Requirement: store a pet's name and age ___ | name: string, age: integer | getAge()

Requirement: an item has a name and cost Item | name: string, cost: _____ | getCost()

Requirement: show a dog's name Dog | name: string, age: integer | _______()

Requirement: a cat's age can be changed Cat | age: integer | ______(newAge)

Requirement: store a car's make and year Car | make: string, ____: integer | getYear()

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A Object: students

B Attr: name: string

C Attr: age: integer

D Method: getAge()

Question 2

A Object: Book

B Attr: title: integer

C Attr: pages: integer

D Method: getTitle()

Question 3

A Need: track a pet's name

B Object: Owner

C Attr: name: string

D Method: getName()

Question 4

A Object: pet_owner

B Attr: name: string

C Attr: phone: string

D Method: getPhone()

Question 5

A Object: Product

B Attr: price

C Attr: stock: integer

D Method: getPrice()

Answer Key

Writing an object description from a requirement

Section A: Quick Questions

A — Book | title: string, pages: integer | getTitle(), getPages()

B — Student | name: string, age: integer | getAge(), setAge(newAge)

B — name: string, weight: float

A — getTotalMarks()

A — getRegistration(), setOdometer(newReading)

Section B: Match the Pairs

Student | name: string, age: integer | getAge(), setAge(newAge) → A complete object description: the object name, its attributes with data types, then its methods

name: string, age: integer → The attributes part of the description: each data item the object stores, with its data type

A requirement says a library must record each book's title and number of pages, so the object is Book and only those two attributes are needed → Book | title: string, pages: integer | getTitle(), getPages()

Methods are named with the same convention as the rest of the program (camelCase), starting with a verb such as get or set → Student | name: string, age: integer | getAge(), setAge(newAge)

Student | name, age | getAge(), setAge(newAge) → The attributes have no data types. They should be written as name: string, age: integer.

Student | name: string, age: integer, favouriteColour: string | getAge() → favouriteColour is not needed by the requirement. Only relevant attributes should be included, so it should be removed.

Section C: Definitions

object description — Names an object, its attributes with data types and its methods, using only what the requirement needs. Example: Student has name: string, age: integer, getAge().

Section D: Fill in the Blanks

Requirement: store a pet's name and age
Pet | name: string, age: integer | getAge()

Requirement: an item has a name and cost
Item | name: string, cost: float | getCost()

Requirement: show a dog's name
Dog | name: string, age: integer | getName()

Requirement: a cat's age can be changed
Cat | age: integer | setAge(newAge)

Requirement: store a car's make and year
Car | make: string, year: integer | getYear()

Section E: Spot the Error

A — An object is named with a singular, capitalised noun because it describes one item. It should be 'Student', not the lowercase plural 'students'.

B — A title is text, so its data type must be string. It should be 'Attr: title: string'.

B — The requirement is about a pet's name, so the object to describe is Pet, not Owner. It should be 'Object: Pet'.

A — Object names use capitalised words joined together with no underscores, so snake case breaks the convention. It should be 'Object: PetOwner'.

B — Every attribute in an object description needs a data type. A price can have cents, so it should be 'Attr: price: float'.